多径信道上基于RIS辅助的物理层认证的安全性分析
Security Analysis of RIS-Assisted Physical-Layer Authentication Over Multipath Channels
AI总结：
研究多径信道上RIS辅助物理层认证安全性，推导攻击者最优策略，分析信道不可区分条件，发现单天线攻击者在多径信道无法满足条件，单路径视距条件下可冒充合法发送者，并进行数值验证和安全性评估。
摘要：
在物理层认证中，用户身份验证基于信号传输到认证器（Bob）的传输信道特性。本文假设Bob接收到的信号通过Bob控制的RIS，合法发送者（Alice）配备一根天线，攻击者（Trudy）有多个天线并使用预编码欺骗Bob验证。假设Trudy知道所有信道矩阵，首先推导其最优攻击策略，然后分析Alice或Trudy发送时Bob估计信道不可区分的条件。当Trudy有单根天线时，表明当到RIS的信道是多径传播结果时，不可区分条件无法满足。对于单路径视距条件，Trudy虽从不同位置发送但可冒充Alice。我们通过数值验证这些结果并评估所考虑场景的安全性，即使不可区分条件无法满足。
英文摘要：
In physical layer authentication, verification of a user's identity is based on the characteristics of the transmission channel through which signals are delivered to the authenticator (Bob). In this paper, we assume that the signals received by Bob pass through a \ac{RIS} (controlled by Bob) and that the legitimate transmitter (Alice) is equipped with one antenna. Conversely, the attacker (Trudy) has multiple antennas and uses precoding to deceive Bob's verification. Assuming that Trudy knows all the channel matrices, we first derive her optimal attack strategy. Then, we analyse the conditions under which the channel estimated by Bob is indistinguishable when either Alice or Trudy is transmitting. When Trudy has a single antenna, we show that the indistinguishability condition cannot be met when the channels to the RIS are the result of propagation over multiple paths. For single-path line-of-sight (LOS) conditions, instead, Trudy can impersonate Alice although transmitting from a different position. We verify these results numerically and assess the security of the considered scenario, even when the indistinguishability conditions cannot be met.
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